It is known that the optoelectrical integrated circuit ("IC") relay mainly comprises a optoelectrical conversion element having a light-emitting means and a light-receiving means which are optical coupling in nature. The optoelectrical IC relay is employed to maintain in an insulated state as long as it is not activated by a condition change. In other words, the condition change means that the light-emitting means is activated by an input current signal, and then the current signal is converted into a light signal for transmitting to the light-receiving means for further converting into an electrical signal. By utilizing this conversion, the optoelectrical IC relay can acts as an isolator, or a noise suppressor in a circuit, or as filtering out noise in the load of a circuit.
In the application of as the isolator, the optoelectrical IC relay is widely implemented in an OR gate, a NAND gate, or a NOR gate of a logic circuit.
It is also implemented in a current source circuit for comparing an output voltage with a predetermined threshold voltage for generating a feedback signal to control the output voltage. As such, the output voltage is maintained at a regulated level. Alternatively, it is implemented as a solid state relay.
In the application of as the noise suppressor, the optoelectrical IC relay is driven in a current mode due to its low input impedance. Such that noise with a high impedance may be filtered out.
As the optoelectrical IC relay employed in the junction of a transistor-transistor-logic ("TTL") circuit and a high-noise-interference-logic ("TNIL") circuit activated by different current sources, noise will not adversely affect the TNIL circuit.
As the optoelectrical IC relay employed in the clipping circuit, the response is acceptable and there is no adverse effect on the signal circuit.
As the optoelectrical IC relay employed to filter out noise in the load of a circuit, noise spike generated in the load side will not feedback to the logic circuit side.
Typically, a layer of opaque material insulated material is coated on the surface of the optoelectrical IC relay for preventing an external light from entering into the light-emitting means, and also preventing light emitted by the light-emitting means from transmitting to the external.
One drawback is that a user can not see the internal elements of the relay for determining whether the relay is normally operated. The only method to determine whether the relay is normal is by pulling the relay out of the operating circuit. Then, conduct a test on it by a testing device. It is quite inconvenient.
Thus, it is desirable to provide an improved optoelectrical IC relay construction to overcome the above drawback.